Then Will heard heard another noise, another rumble in the distance, like the wrath of a volcano. Pezzulo backed up a few feet and braced himself for another collapse. "Oh, my God," Will said. "Here we go again." The north tower came down around them. It was 10:28.

From above, a jagged block of concrete fell through the hole and tumbled into their crawl space. Will watched as the slab struck Pezzulo and "laid him down like a rag doll." Pezzulo withered in pain. He made a wisecrack to the sergeant, something about requesting permission to take a coffee break. He was losing a lot blood. He turned and said, "I love you, Will."

Will said, "I love you, buddy."

"Don't forget," Pezzulo added. "Don't forget I died trying to save you guys."

Then Pezzulo unholstered his 9mm sidearm, pointed it up toward the hole, and fired off a single round. "It was like a last ditch effort," Will says, "as if to say, We're down here, come find us."

Will watched as Pezzulo slumped back and gasped for air. His gun fell to his side.

John McLoughlin, unable to see anything down in his black hole, shouted through the pain, "What's going on up there?"

"Sarge - it's Dom. He's gone. I just saw him pass."

***

A team of plastic surgeons at Saint Vincent's sutured Silvion Ramsundar's chin back together. Then they went to work on his chest. His shoulder blade was broken, and the piece of shrapnel was lodged dangerously close to his aorta. The doctors worried that if they weren't extremely careful in removing the object, they could paralyze his arm for life. One they dug out the gobbet with their surgical tools and examined it, the doctors decided it was a shard of metal from the airplane that crashed into his floor. Silvion wanted to keep it - a piece of that day once embedded in his body - but later an FBI agent arrived with Ziploc bag, marked it EVIDENCE, and carried the artifact away.

***

When Ronnie Clifford arrived home in the late morning, he embraced Bridget, and then climbed upstairs straightaway for a shower. More than anything else, he wanted to rinse off the residue of his morning. At least he had his daughter's birthday party to look forward to. He paused to think about what his would mean for Monica as she grew up, to have turned eleven on September 11th, 2001. Monica was across the street at school - innocent, for now, of what had transpired in the city.

Ronnie, it turned out, was innocent, too. He had assumed it was only fair, after witnessing so much, after doing his part as a good Samaritan, that he should sail away on the Hoboken ferry, unscathed. But then he received a piece of news by phone from his brother-in-law that, with a bit of work on the internet, he confirmed. Among the ticketed passengers on American Airlines Flight 11, the first plane, the one that hit the north tower, had been Paige Farley-Hackel, his sister Ruth's best friend, and a close friend of his. A little later in the afternoon he was able to verify an even more devastating fact: Ruth and her four-year-old daughter, Juliana, had been on the second plane, the United Airlines flight from Boston.

Ronnie had somehow lost track of when Ruth and Juliana were supposed to fly to Los Angeles. He thought they'd gone out the day before. Paige had intended to fly with Ruth, but there'd been some kind of mix-up at Logan. Paige took American, Ruth took United, but they both ended up in the hands of hijackers, friends in separate missiles aimed at the same target.

Ronnie tried to imagine Ruth's last moments on the plane. Most likely, Ronnie thought, she would have been sitting calmly in her seat as they banked low over the Hudson. And in the seconds before the plane hit, she would have been holding little Juliana, and singing a song in her ear.

***

Will Jimeno and Sergeant McLoughlin were the only ones left. Amoroso, Rodriguez, and now Pezzulo were all dead. The two men waited for hours for something to happen. Occasionally fireballs floated down into the hole and landed beside them and then extinguished themselves in the wreckage. One of them must have landed near Pezzulo's Smith & Wesson and heated it up. The gun went off, and bullets ricocheted around the hole. "You're not going to believe this, we're getting shot at!" Will yelled to McLoughlin.

They talked to each other a lot during the afternoon, the veteran sergeant and the rookie. They talked about their families, about life and death, about their buddies who lay buried about them. Both men were in agony, squirming under the pressure, their arms and legs swelling. But they were lucid. With his free hand, Will tried to chip away at the concrete with his handcuffs and spare magazine of his gun. It was useless. Every couple of minutes he would yell out, PAPD 813!" which is Port Authority code for officer down. But as midday stretched into late afternoon his calls began to lack enthusiasm.

Then, from the hole above, Will heard a voice. Someone was frantically shouting a name, then, "Are you down there? Are you down there?"

Will couldn't catch the name, but he shouted back—"Sergeant McLaughlin and Officer Jimeno are here!" He was ecstatic. But then the voice left and never returned.

Will began to talk to himself out loud, a stream of dire thoughts. He thought about Allison, his wife, who was seven months pregrant. "At that point I pretty much accepted death," he says. "I asked God to watch over Allison and my little four-year-old and the new baby girl. I wanted to see the baby, just once."

At around 8:00, Will was aroused by another voice. "United States Marine Corps, can anybody hear me?"

Will yelled back, "Don't leave us! The last guy left us."

Then a marine trained his flashlight into the hole and spotted him. "I'm not leaving you," he said.

Soon the paramedics came, and firemen and cops and Port Authority officers, a long trail of men harnessed to one another, clambering over the pile. For three hours they dug and scraped and sawed, pulling away the rebar, widening the hole. They used bare hands, welding torches, buzz saws, the Jaws of Life. Finally, they reached Will. They feared they would have to amputate his left leg, but at last budged the pillar just enough to slip him free.

They would get to McGlaughlin, but first they slide Will into a basket and hauled him out. It was 11:00 at night, thirteen hours after the south tower had collapsed. Will looked around at the devastated site, a smoky panorama of harsh lights and humming generators and flickering welders' sparks.

"Where is everything?" he asked.

One of the officers leaned over and said to him, "There's nothing left, kid. It's all gone."

***

Later in September, Ronnie Clifford went to visit Jennieann at the hospital. She was wrapped in gauze from head to toe, save for narrow slits for her eyes and her mouth. Although Jennieann was heavily sedated and could not talk, her sister said she was aware of visitors. Ronnie sat with her for awhile, and urged her to be strong. Before he left, he placed his yellow silk tie on the pillow beside her, the tie he'd been wearing on the eleventh, the one Ruth had coached him to wear. Ronnie wasn't sure why this gesture had occurred to him. He just wanted for her to have something to remember him by. Something that stood out.

Jennieann was in the hospital for forty-one days, drifting in and out of consciousness. The mounting infections, the skin grafts, the side effects of her medications - it was all too much for her system. On October 21, she died of kidney failure.

The same day, workers at Ground Zero located Ruth's remains. The family had already held a service for her and Julia a month earlier. More than twelve hundred people showed up. There had been long bittersweet remembrances and a Celtic bagpiper. Ronnie organized a huge party afterward on Ruth's front lawn.

As soon as he got home from the funeral, Ronnie collapsed in exhaustion. "My emotions were swimming around," he says. He was a nervous wreck. One time Monica and a friend were horsing around on the hardwood floor and made a sharp thumping sound. Ronnie completely lost it. All he could think of was falling bodies, the woman with her purse. He couldn't get the images out of his head.

Finally recognizing that the problem was "far greater than anything I could deal with," Ron went to a psychologist's office. Doug, the therapist, sat back in his reclining chair and invited him to talk about his life. He asked Ronnie to keep a journal of his dreams. He put him under mild hypnosis and had him relive every sight and smell and sensation of that horrible day. What started out as six hours a week has since fallen away to one hour every other week. The engineering metaphor has proved apt.

***

Mostly, Silvion Ramsundar misses the views. The way electrical storms scudded out to the Atlantic, the sunsets that went on forever, the morning sun lighting up the clustered spires of lower Manhattan, the Statue of Liberty standing sentinel at his feet.

Silvion spent two weeks mending in the hospital, followed by months of physical therapy to restore his shoulder. The arm still tingles and throbs, and it bothers him in countless little ways. As he talks, he twists and flexes his arm. "They say it's never going to be 100 percent," he says. "It gets all locked up. I can't pick Mariah up the way I used to, to take her to bed. But they say, just be grateful you can use your arm at all."

When he arrived home from the hospital, Silvion didn't relive the incident, exactly, but he had bad dreams: He kept finding himself trapped in a fire, smashing up his car, being chased. Then he started having anxiety attacks whenever he drove over a bridge. In daydreams and reveries, Silvion can still summon the sight of the Sky Lobby with sickening vividness. That he survived the blast through nothing more than dumb luck, an accident of position, troubles him. "There was only one quadrant on that floor that was safe from the plane, and it happened to be where I was standing," he tells me, with fresh amazement. "If I'd been standing ten feet to my left, maybe I wouldn't be sitting here. Had I been a foot to my right, maybe the debris would have hit my heart. Why me? Why not the guy standing next to me. How come I was in the right place?"